Field of the Invention
The present invention relates to an electrophotographic member to be used in an electrophotographic apparatus, and a process cartridge and an electrophotographic apparatus each including the electrophotographic member.
Description of the Related Art
In an electrophotographic apparatus (such as a copying machine, facsimile, or printer employing an electrophotographic system), an electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”) is charged by a charging member and exposed by a laser or the like, and as a result, an electrostatic latent image is formed on the photosensitive member. Next, toner in a developer container is applied onto a developer carrying member by a toner-supplying roller and a toner-regulating member. The electrostatic latent image on the photosensitive member is developed with the toner conveyed to a developing region by the developer carrying member at a portion in which the photosensitive member and the developer carrying member are in contact with, or close to, each other. After that, the toner on the photosensitive member is transferred onto recording paper by a transfer unit, and is fixed by heat and a pressure. In addition, the toner remaining on the photosensitive member is removed by a cleaning blade.
In the electrophotographic apparatus as an image-forming apparatus adopting the electrophotographic system, an electro-conductive member has been used in various applications, e.g., electro-conductive rollers such as a charging roller, a developing roller, and a transfer roller. The electrical resistance value of any such electro-conductive roller is controlled to from 105Ω to 109Ω. In addition, an electro-conductive layer having added thereto an ionic electro-conductive agent such as a quaternary ammonium salt compound is provided for the adjustment of any such roller to such electro-conductivity.
An ionic electro-conductive member obtained by adding the ionic electro-conductive agent can reduce the non-uniformity of the electrical resistance value resulting from non-uniform dispersion of the electro-conductive agent as compared to an electronic electro-conductive member. Accordingly, a low-resistance site hardly occurs in the electro-conductive layer in a local manner.
Meanwhile, the ionic electro-conductive agent such as a quaternary ammonium salt or an alkali metal salt may bleed to the surface of an electro-conductive roller (hereinafter referred to as “bleeding”). As a result, a change in outer diameter dimension of the electro-conductive roller, an increase in property by which dirt adheres to the surface of the electro-conductive roller, and the contamination of the surface of any other member to be brought into contact with the electro-conductive roller may occur. In addition, a desired resistance value may not be obtained under a high-temperature and high-humidity environment or a low-temperature and low-humidity environment because the resistance of the roller is liable to fluctuate depending on an environment.
Japanese Patent No. 4193193 discloses a method involving using an ionic liquid having a specific chemical structure as a method for the suppression of the bleeding of the ionic electro-conductive agent and the suppression of the fluctuation in resistance with an environment. In addition, Japanese Patent No. 4392745 discloses a method involving using an ionic liquid having specific physical properties.